DIY Sabatier Reactor: Capturing Carbon Dioxide with Magnesium Oxide

[CCatalyst]

TL;DR Summary

Fighting climate change while making money at the same time.

We all are aware of the looming danger of climate change and so I want to do my part. I plan to capture the carbon dioxide from the air using magnesium oxide, turning it into magnesium carbonate, and then heating it up to reverse the process while capturing the carbon dioxide. The Sabatier reactor is quite simple, just a tube made of nickel that can handle the heat and pressure. Then is where the tricky part comes in, the water and methane enter a chamber with high temperature and low pressure. Here I want to use heat to break down the methane and let the carbon settle at the bottom. The difficulty comes with dealing with the water. I guess I will let it vent out towards the external burner used to break the methane inside down along with the extra hydrogen as it is interacting with atmospheric oxygen. I will attempt to use electricity to recapture the hydrogen and reuse it for the cycle while releasing as much as the oxygen as possible. However, I'm not sure how high of temperature an electrolyzer can operate at.

I know this will take electricity to run, but I plan to buy a solar-charged battery pack. The real hard part is integration and parts compatibility. I don't want to spend a lot of money on something just to find out it cannot work with other parts. As for the carbon, I plan to sell it.

Also, I would like to keep this simple, this way many people could do this. Any questions or suggestions?

 

[trurle]

Magnesium oxide-based carbon dioxide capture generally too problematic at industrial scale due sluggish kinetics and high recycling temperature; NASA do use manganese oxide for carbon dioxide scrubbers though.

 

[Rive]

As for the carbon, I plan to sell it.

If I take that right you plan to invest a lot of energy to capture carbon dioxide (save the planet) and then sell the carbon - which then will be likely burned?

I think selling the methane instead would be a bit less disastrous financially. But not by much.

Just selling the output of you solar power would work. That would also at least make a (slightly) negative carbon balance. Maybe.

 

[berkeman]

If I take that right you plan to invest a lot of energy to capture carbon dioxide (save the planet) and then sell the carbon - which then will be likely burned?

Mmm, burgers...

https://www.appliancesonline.com.au.../71123/extrnl/Weber-Briquettes-10KG-high.jpeg

 

[CCatalyst]

I do not want to sell the carbon to be burned again, I want it to be used to build stuff, like carbon fibers.

Also, I cannot find a lower temperature regenerative carbon dioxide scrubber than magnesium oxide. Besides, if I were to use manganese it would release the even MORE dangerous carbon monoxide.

Any more suggestions?

 

[trurle]

I do not want to sell the carbon to be burned again, I want it to be used to build stuff, like carbon fibers.

Also, I cannot find a lower temperature regenerative carbon dioxide scrubber than magnesium oxide. Besides, if I were to use manganese it would release the even MORE dangerous carbon monoxide.

Any more suggestions?

Add catalytic filter with counter-flow reheater at manganese-based scrubber output if you are concerned with CO emission; Space Shuttle manganese-based scrubbers did not emit CO though.
Or use ethanolamine scrubber.

Actually i understand what all existing CO2 scrubber technologies, especially ones which use natural air as input, are either extremely bulky or require expensive material input. It would be a challenge to develop a technology clearly superior to bioreactors or trees.

Also, carbon fiber is not made of bulk carbon - you need either coal tar or PAN plastic as input.

 

[anorlunda]

If you want to capture carbon and have something to sell to build things, plant a tree.

Almost all the weight of a dried tree is captured carbon.

 

[trurle]

If you want to capture carbon and have something to sell to build things, plant a tree.

Almost all the weight of a dried tree is captured carbon.

To be exact, dry cellulose can be decomposed as 44% carbon and 56% water.

 

[Rive]

I want it to be used to build stuff, like carbon fibers.

In short: the efficiency is so low and the necessary equipment is so complicated, that it will inevitably end with a terrible carbon balance. Having released ten times of carbon compared to the 'captured' amount might still be an optimistic assumption.

I do agree with @anorlunda : if you want to save the planet, then rather plant a tree.

If you want to have fun with a small scale DIY project, then we are happy to keep you company here.

 

[TeethWhitener]

FYI Stuart Licht at GWU has done a lot of work in this direction:
https://blogs.gwu.edu/slicht/solar-research/
They use molten carbonate cells to reduce CO₂ to useful carbon products.

 

[TeethWhitener]

Also there's a ton of work being done on artificial photosynthesis/photoelectrochemical reduction of CO₂ for fuel synthesis.

 

[CCatalyst]

Every time I am given an alternative to magnesium oxide, I am recommended something that is more complex and dangerous.

The hard part right now for me is to find nickel tanks that I can take apart before and after use. Where do I go to buy a small one of those?

 

[anorlunda]

Summary: Fighting climate change while making money at the same time.

We all are aware of the looming danger of climate change and so I want to do my part. I plan to capture the carbon dioxide from the air using magnesium oxide, turning it into magnesium carbonate, and then heating it up to reverse the process while capturing the carbon dioxide

Let's start with the basics. How many pounds of carbon per year do you need to capture to declare it a success?

 

[Bystander]

Let's start with the basics. How many pounds of carbon per year do you need to capture to declare it a success?

..., and how many tons of air, @400ppm, do you need to process to achieve that target? Can you pump it across the room for the energy you produce?

 

[TeethWhitener]

Every time I am given an alternative to magnesium oxide, I am recommended something that is more complex and dangerous.

...it almost sounds like you’re asking us not to help you.

If all you want to do is fix carbon, just do it electrochemically. You can use a 9V battery and a platinum wire. If you want to do it efficiently, well...take a look at the work of the thousands of researchers trying to do just that. I gave you two examples of that.

 

[CCatalyst]

...it almost sounds like you’re asking us not to help you.

I would accept your help if the advise would not make things more dangerous.

Right now, I am having a very hard time finding the parts I need for this. Where can I buy nickel boxes that are air-tight that can be heated up? Ones that have inlet/outlet lines. Let's just focus on that right now.

 

[anorlunda]

Ones that have inlet/outlet lines. Let's just focus on that right now.

No. Let's focus on the earlier questions that you haven't answered.

How much carbon are you trying to fix? How much energy can you spend? Home much money can you spend? Compare you ambitions with trees.

 

[CCatalyst]

I want the containers to be around two liters or less. If this produces ANY raw carbon it will be a success. Now how do I obtain the parts I need?

 

[CCatalyst]

I hate to double post but how hot does methane have to be in order to break down? I've seen figures from 700C to 1000C. So what temperature do I need for it to break down in the absence of oxygen, but in the presence of nickel or a nickel alloy?

Also, I've read that with the right catalysts, breaking down methane can create multi-walled nanotubes. Now, some places say they cause cancer, while others say it is used to TREAT cancer. Now, if I end up creating nanotubes from this, what do I have to do to prevent myself from developing cancer?

 

[chemisttree]

To prevent cancer, use PPO and conduct experiments in a ventilated hood equipped with particulate filters.

To find out the cracking temperature of methane in the presence of nickel alloys, you’ll need to do the research yourself. You will likely produce carbon that could be best described as “fouling”. Search the literature for antifouling and gas reforming to find out the technology behind reducing this otherwise troublesome problem. You will also learn about the conditions that produce this fouling which for some reason seems to be the goal you wish to achieve.

Good luck with it!

Oh, I almost forgot to add that you might want to start with a nickel alloy pipe reactor inside a tube furnace. Good Googleage to you!